“Release the mainsail! That one there!” shrieks Alfie, his voice shot through with fear, and I unwrap the rope from the hooks as quickly as I can. Immediately the boom swings round, the sail flaps loose, and I can feel a lessening of the boat’s speed, but it’s still hurtling toward the rocks under its own momentum. The rocks shield a little bay and at any second we’ll be thumping down onto them like the waves, which are throwing up huge plumes of white spray.

Alfie turns the boat’s wheel clockwise as fast as he can; his hands are a blur, and the boat lurches to the right. Meanwhile, in the doorway, another strand of the rope pings apart as Jasper continues his frantic sawing.

“You thieving rats!” he growls. “Wait till I get my hands on you!”

“Take the wheel!” shouts Alfie, and as soon as I do, he’s pulling off his sweater and kicking off his shoes.

“What the…?”

Everything is happening so fast. At exactly the moment that Alfie dives over the side into the churning sea, disappearing beneath the surface, the final strand of rope succumbs to the pressure of Jasper’s knife and the door bursts open.

I start to yell, “Alfie!” but I don’t get past the first syllable and end up just screaming.

The Jolly Roger is still continuing its terrifying progress toward the land when a huge swell from a wave lifts us up and away from a massive black rock. Water cascades over the side of the boat, and if I wasn’t clinging on to the wheel, I’d be cast overboard.

Seconds later, the yacht has righted itself, but with no wind in the sails we’re at the mercy of the ocean, which will surely take us back to the looming rocks.

Jasper, who has not even said anything yet, grabs the rope attached to the sail. It’s like an instinct to save himself and his boat, tightening the rope enough to give the sail some wind to work with, and as he secures it to the metal hook again, the Jolly Roger begins an agonizing, slow curve away from the rocks. The wind is still howling and the rain is hammering so hard into my face that I can hardly see.

All the while, from the boat’s speakers comes the monks’ slow, harmonious chanting.

There’s so much going through my head that I can’t even think straight.

The main thing, though, is Alfie. Where is he? Is he OK?

Wiping the sea spray and rain from my face, I try to focus on where he might be in the water, but I can’t even make out where we are. In the last few seconds, the boat has moved many yards away from where he dived in.

Fifty yards. That’s about how far we are from land.

I can swim fifty meters, I’m thinking. Most kids I know can swim at least fifty meters. That’s two lengths of Tynemouth pool. Easy-peasy.

But in open water, in a North Sea storm? He doesn’t stand a chance. It seems, though, that our little boat is out of immediate danger. The rocks and the island are retreating, and still the holy, haunting music is blaring.

Then Jasper’s next to me, screaming in my face.

“WHAT IN GOD’S NAME ARE YOU DOING, AIDAN?”

The full answer to that is going to take much longer than I think Jasper has time for, and I’m not thinking rationally. I just say, “Alfie!”

Jasper looks at me, then at the island, then at the Coast Guard boat, which is now only a couple of hundred meters away. His mouth gapes open for a second and he blinks hard.

“Oh no. Oh no, no, no, no!”